The occurrence of spin-Hall magnetoresistance (SMR) in platinum (Pt) on top of yttrium iron garnet (YIG) has been investigated, for both in-plane and out-of-plane applied magnetic fields and for different Pt thicknesses [3, 4, 8, and 35 nm]. Our experiments show that the SMR signal directly depends on the in-plane and out-of-plane magnetization directions of the YIG. This confirms the theoretical description, where the SMR occurs due to the interplay of the spin-orbit interaction in the Pt and the spin-mixing conductance at the YIG/Pt interface. Additionally, the sensitivity of the SMR and spin pumping signals on the YIG/Pt interface conditions is shown by comparing two different deposition techniques (e-beam evaporation and dc sputtering).

We show the experimental observation of the platinum thickness dependence in a hybrid yttrium iron garnet/platinum system of the inverse spin-Hall effect from spin pumping, over a large frequency range and for different radio-frequency powers. From the measurement of the voltage at the resonant condition and the resistance of the normal metal layer, a strong enhancement of the ratio of these quantities has been observed, which is not in agreement with previous studies on the NiFe/platinum system. The origin of this behaviour cannot be fully explained by the spin transport model that we have used and is therefore still unclear.

The effective field torque of an yttrium-iron-garnet (YIG) film on the spin accumulation in an attached platinum (Pt) film is measured by the spin-Hall magnetoresistance (SMR). As a result, the magnetization direction of a ferromagnetic insulating layer can be measured electrically. Experimental transverse and longitudinal resistances are well described by the theoretical model of SMR in terms of the direct and inverse spin-Hall effect, for different Pt thicknesses [3, 4, 8, and 35 nm]. Adopting a spin-Hall angle of Pt ${\theta }_{\mathit{S}\mathit{H}}=0.08$ , we obtain the spin diffusion length of Pt ($\lambda =1.1\pm 0.3\hspace{0.17em}\text{nm}$ ) as well as the real ($G_r=(7\pm 3)\times {10}^{14}\hspace{0.17em}{\Omega }^{-1}{\mathrm{m}}^{-2}$ ) and imaginary part ($G_i=(5\pm 3)\times {10}^{13}\hspace{0.17em}{\Omega }^{-1}{\mathrm{m}}^{-2}$ ) of the spin-mixing conductance and their ratio ($G_r/G_i=16\pm 4$ ).

This paper presents the frequency dependence of the spin-current emission by spin pumping in a hybrid ferrimagnetic insulator/normal metal system. The system is based on a ferrimagnetic insulating thin film of yttrium iron garnet (YIG, 200 nm) grown by liquid-phase epitaxy coupled with a normal metal with a strong spin-orbit coupling (Pt, 15 nm). The YIG layer presents an isotropic behavior of the magnetization in the plane, a small linewidth, and a roughness lower than 0.4 nm. Here we discuss how the voltage signal from the spin-current detector depends on the frequency (0.6\char21{}7 GHz), the microwave power, Pin (1\char21{}70 mW), and the in-plane static magnetic field. A strong enhancement of the spin-current emission is observed at low frequencies, showing the appearance of nonlinear phenomena.

We demonstrate large increases of the real and imaginary parts of the microwave effective complex permittivity of a series of $\left(\text{piezoelectric}\right)\mathrm{Ba}\mathrm{Ti}{\mathrm{O}}_3∕\left(\text{magnetostrictive}\right)$ Ni nanocomposites under the action of a magnetic field, by about 10% at $2\mathrm{kOe}$ and 300% at $5\mathrm{kOe}$ , respectively. We suggest that the magnetic field dependence of the effective permittivity is consistent with a magnetoelectric effect which can be qualitatively understood within a model in which the piezoelectric phase is mechanically coupled to the magnetostrictive phase.

We present a comprehensive study of the magnetic and microwave properties of piezoelectric ${\text{BaTiO}}_3$ /magnetostrictive Ni nanocomposites (NCs), fabricated under uniaxial compression, at room temperature. In the current work, we investigated samples in the compositional range between $0\le f_{\text{Ni}}\le 33.5\text{vol}\%$ and from 0.1 to 6 GHz using broadband microwave spectroscopy in combination with atomic and magnetic force microscopy (MFM), x-ray diffraction (XRD), electron transport, and broadband (6–28 GHz) ferromagnetic resonance (FMR) experiments in the microwave regime to correlate magnetization dynamics, electromagnetic materials parameters, and microstructural information. The static magnetic response is consistent with a model of a composite medium with an unmodified Ni phase in a nonmagnetic matrix. We provide the experimental evidence for a magnetoelectric (ME) effect, i.e., the effective permittivity at microwave frequencies can be controlled by an external magnetic field, which makes these nanostructures ready for microwave tunable devices, sensors, and transducers. We show in the analysis that this magnetic field dependence is inconsistent with expectations from magnetoresistance and magnetocapacitance effects, and propose as an alternative an explanation based on the striction across the interfaces between the magnetic and piezoelectric phases. By varying the Ni content and frequency, room temperature broadband FMR was performed in order to investigate the different contributions, e.g., inhomogeneous broadening, to the effective linewidth and microwave damping. The line broadening and asymmetry of the FMR features are not intrinsic properties of the metallic nanophase but reflects the local nonmagnetic environment in which they are embedded. The increase in the effective Gilbert damping coefficient as function of the Ni content is related to the strong increase in the damping experienced by the precessing magnetization in the Ni phase. One of the characteristic features of the present results is the significant correlation between the internal field probed by FMR and the ME coupling coefficient evaluated by microwave spectroscopy which was not observed in our previous study of ZnO/Ni NCs. The present results highlight the strong influence of interfaces of the composite constituent play a crucial role in the analysis of the ME coupling. In addition MFM has been successfully used to detect the strong magnetic contrast between the phases of these nanostructures which indicates local changes in composition and structure.